During manufacture of an aluminium alloy wheel, wheel spraying is an indispensible process to ensure its corrosion resistance and a customer's requirement for appearance. However, in spraying, as a spray head of a spray gun is stationary, wheels on an assembly line not only need to be rotatable, but also must be capable of being jacked up when reaching below the spray gun, to reach an optimum distance between the wheel and the spray gun; in addition, thickening and clogging of bolt hole protection plugs are prone to occur after completion of wheel spraying, making removing the bolt hole protection plugs manually inconvenient. In summary of the above analysis, the present invention completely solves all problems at present.